Providing both I2 (image intensified) and FLIR (forward looking infrared) images on a helmet-mounted
display (HMD) requires perceptual design tradeoffs. Primary considerations center on the number, type,
and placement of sensors. Perceptual drivers for these tradeoffs are derived from monocular versus
biocular/binocular displays and offset of the sensors from the design eye. These conditions can create
binocular rivalry, perceptual perspective distortion or hyperstereopsis, a binocular perceptual distortion that
occurs when the sensors are positioned further apart than the interpupillary distance (IPD). Each of these
perceptual tradeoff considerations is discussed.